BeagleBone Black Time Server

Stratum 1 GNSS NTP Server running on a BeagleBone Black

Equipment

These are the parts I have used.

BeagleBone Black
SparkFun ublox NEO-M9N
- I went a little overkill on this one, but this module supports GPS, GLONASS, BeiDou, and Galileo
- This Adafruit module is a good alternative
Adafruit DS3231 RTC
Some cheap Active GPS Antenna
uFL to SMA Adapter Pigtail (Example)
Pin Headers for the GNSS module (Soldering required)
Some Male-to-Female DuPont Cables

Wiring

BBB	GNSS Module
5V	5V
GND	GND
P9_11 (UART4_TX)	RX
P9_13 (UART4_RX)	TX
P9_12 (GPIO 60)	PPS

Setup

Install Debian Minimal on the BeagleBone Black
Install packages:

sudo apt update
sudo apt install git build-essential pps-tools gpsd chrony nginx php-fpm php-gd

Compile PPS device tree

Clone bb.org-overlays repo:

git clone https://github.com/beagleboard/bb.org-overlays

Copy DD-PPS-00A0.dts into cloned bb.org-overlays/src/arm/.

Compile .dtbo and place in /lib/firmware:

make src/arm/DD-PPS.dtbo
sudo cp src/arm/DD-PPS.dtbo /lib/firmware

Edit /boot/uEnv.txt:

###Overide capes with eeprom
uboot_overlay_addr0=/lib/firmware/BB-I2C2-RTC-DS3231.dtbo
uboot_overlay_addr1=/lib/firmware/BB-UART4-00A0.dtbo
uboot_overlay_addr2=/lib/firmware/DD-PPS.dtbo

Reboot to apply changes.
Setup GPSd

Edit /etc/default/gpsd. Use file in this repo as reference.

Start GPSd:

sudo systemctl start gpsd
sudo systemctl enable gpsd
systemctl status gpsd

Check using gpsmon and cgps commands.

Setup Chrony

Edit Chrony config files. Use file in this repo as reference.

Start GPSd:

sudo systemctl start chrony
systemctl status chrony

Check using chronyc tracking, chronyc sources -v, and chronyc sourcestats -v commands.

(Optional) Setup nginx + php to serve /var/www/html.

Photos

Time Page

This is the html website included in this repo. In concept, it is similar to time.is.

References

My setup is based off the following guides, very thankful for them.